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參數(shù)資料
| 型號： | SSM2120 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 模擬信號調(diào)理 |
| 英文描述： | Dynamic Range Processors/Dual VCA |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDIP22 |
| 封裝： | PLASTIC, DIP-22 |
| 文件頁數(shù)： | 10/12頁 |
| 文件大小： | 371K |
| 代理商： | SSM2120 |
SSM2120/SSM2122
REV. C
–10–
V+
LOG AV
V–
SIGNAL
INPUT
SIGNAL
OUTPUT
160k
IN |I
IN
|
REC
IN
39k
1.5M
1k
C
AV1
V–
+V
C
–V
C
2200pF
47
36k
36k
100pF
12k
CON
OUT
V–
200
200
THRESHOLD
160k
39k
1k
CON
OUT
V–
F
C
≤
20Hz
36k
5.6k
36k
R
IN1
V+
V+
LOG AV
IN |I
IN
|
REC
IN
1.5M
C
AV2
V–
F
C
= 5Hz
R
IN2
36k
+V
C
–V
C
36k
200
200
12k
2200pF
47
DOWNWARD EXPANDER
Figure 14. Dynamic Filter with Downward Expander
DYNAMIC FILTER WITH DOWNWARD EXPANDER
A composite single-ended noise reduction system can be
realized by a combination of dynamic filtering and a downward
expander. As shown in Figure 14, the output from the wideband
detector can also be connected to the +V
C
control port of the
second VCA which is connected in series with the sliding filter.
This will act as a downward expander with a threshold that
tracks that of the filter. Although both of these techniques are
used for noise reduction, each alone will pass appreciable
amounts of noise under some conditions. When used together,
both contribute distinct advantages while compensating for each
other’s deficiencies.
Downward expansion uses a VCA controlled by the level
detector. This section maintains dynamic range integrity for all
levels above the user adjustable threshold level. As the input
level decreases below the threshold, gain reduction occurs at an
increasing rate (see Figure 15). This technique reduces audible
noise in fade outs or low level signal passages by keeping the
standing noise floor well below the program material.
This technique by itself is less effective for signals with
predominantly low frequency content such as a bass solo where
wideband frequency noise would be heard at full level. Also,
since the level detector has a time constant for signal averaging,
percussive material can modulate the noise floor causing a
“pumping” or “breathing” effect.
The dynamic filter and downward expander techniques used
together can be employed more subtly to achieve a given level of
noise reduction than would be required if used individually. Up
to 30 dB of noise reduction can be realized while preserving the
crisp highs with a minimum of transient side effects.
+20
–30
–40
–50
–60
+20
–30
–45
–60
–75
I
O
Figure 15. Typical Downward Expander I/O Characteristics
at –30 dB Threshold Level (1:1.5 Ratio)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SSM2122 | Dynamic Range Processors/Dual VCA |
| SSM-2134 | LOW NOISE AUDIO OPERATIONAL AMPLIFIER |
| SSM2134 | LOW NOISE AUDIO OPERATIONAL AMPLIFIER |
| SSM-2404 | Quad Audio Switch |
| SSM2404 | Quad Audio Switch |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SSM-2120 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dynamic Range Processors/Dual VCA |
| SSM2120P | 制造商:Analog Devices 功能描述:DUAL VOLT ATTENUATOR 2120 DIP22 |
| SSM2122 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dynamic Range Processors/Dual VCA |
| SSM-2122 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dynamic Range Processors/Dual VCA |
| SSM2122P | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Amplifier. Other |
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